1. Field of the Invention
The invention relates to a metal shearing machine which cuts a workpiece simultaneously along two intersecting lines.
More specifically, the invention relates to such a machine which provides a novel movable carriage means for the workpiece which ensures more accurate alignment of the workpiece with the shearing blades and permits the handling of heavier workpieces.
In addition, the invention relates to such a machine having an improved support and actuating system for the blade carrying ram.
Further, the invention relates to such a machine which includes means for sensing and manipulating the position of the workpiece on the carriage means whereby to more accurately align the workpiece with the cutting blades.
2. Description of Prior Art
Metal shearing machines which cut simultaneously along two intersecting lines are known in the prior art as illustrated in, for example, U.S. Pat. Nos. 3,691,887, Roch, Sept. 19, 1972, 3,821,914, Roch, Jul. 2, 1974, and 3,877,332, and Roch, Apr. 15, 1975 (all of which are related patents and have the same teachings and are henceforth referred to as the Group I patents), U.S. Pat. Nos. 3,828,639, Roch, Aug. 13, 1974 and 3,942,400, Roch, Mar. 9, 1976 (which are related patents and have the same teachings and are henceforth referred to as the Group II patents), U.S. Pat. No. 3,874,260, Roch, Apr. 1, 1975, U.S. Pat. No. 4,297,927, Kuroda, Nov. 3, 1981 and U.S. Pat. No. 4,519,284, Hunter et al, May 28, 1985.
The Group I patents teach a machine having a three point support system for the blade carrying ram. With such a support system, the size of the blade which can be accommodated is limited as, with larger blades, shearing stability decreases thereby increasing distortions in the sheared material. The workpiece in the Group I patents is carried by fingers 38 extending from carriage 36. Fingers 38 are movable in the carriage 36 to move the workpiece 21 in the direction indicated by arrow 22 in FIG. 4 of these patents, and carriage 36 is movable in the direction transverse to the direction of arrow 22 to move the workpiece in the transverse direction. Because the fingers are carrying the full weight of the workpiece, the size (weight) of workpiece which can be handled by the machines according to the Group I patents is limited.
The Group II patents also teach a machine having a three point ram support. A workpiece is mounted on a table top 16 (see FIG. 1) and is gripped by grippers in carriage 17.
U.S. Pat. No. 3,874,260 teaches a method and apparatus for removing final blanks sheared from a sheet. A conveyor, adjacent the intersecting lower blanks, is tipped downward to accommodate the downward movement of the upper shearing blades, to thereby receive the sheared blank and convey it away from the blades. The problems dealt with by the present application are not dealt with in the '260 patent.
U.S. Pat. No. 4,297,927 teaches an arrangement similar to the arrangement of the Group I patents above-described. Specifically, grippers 44 and 46 (see FIG. 1 of the patent) are mounted on a carriage 42 for movement along the work table 40. A slider 41 (see FIG. 2) is also mounted on the carriage for movement across the work table. This complicated arrangement is used for the purpose of precisely positioning the workpiece. Once again, the full weight of the metal workpiece must be supported by the grippers 44 and 46.
U.S. Pat. No. 4,519,284 teaches a transverse gripper assembly 46 and a longitudinal gripper assembly 48 (see FIG. 1 of the patent). The workpiece is gripped by one gripper assembly at a time to move along the appropriate axis. Thus, if it is necessary to move the workpiece transversely, it is gripped by the gripper assembly 46 (but not the gripper assembly 48). To be moved in the longitudinal direction, it is gripped by the gripper assembly 48 (but not the gripper assembly 46). Thus, once again, a complicated arrangement is needed for precisely positioning the workpiece. Also, once again, the workpiece is supported solely by the grippers so that the size (weight) of workpiece which can be manipulated by these machines is limited as in the Group I patent.